| 摘要 |
PROBLEM TO BE SOLVED: To prevent the loss of silicon in a silicon wafer and the phenomenon of an impurity redistribution on the wafer from being generated by a method wherein an oxide film for protecting the upper part of the silicon wafer is formed by injecting virgin gas and silicon gas in the upper part of the wafer. SOLUTION: Virgin gas, which is under heating, such as N2 O gas, and silicon gas, such as SiH4 gas, are injected in the upper part of a wafer 11 to form an oxide film 12. Then, the temperature in a chamber is made to drop while N2 O gas only is fed in the chamber and after the feed of the N2 O gas is stopped, SiH4 gas is again fed to form a polysilicon film 13. NH3 gas is injected in the upper part of the film 13 and a silicon nitride film 14 is formed on the upper part of the film 13. Then, after patterning is performed, the films 14 and 13 are etched and exposed parts are oxidized to form an oxide film 15. Therefore, the consumption of silicon in a silicon wafer is reduced and a field oxide film, in which an impurity distribution is never deformed, of a semiconductor device can be obtained.
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